package com.yangjicong.project.common;

import org.springframework.beans.factory.DisposableBean;
import org.springframework.context.ApplicationContext;
import org.springframework.context.ApplicationContextAware;

import java.io.File;
import java.io.IOException;
import java.util.Objects;

public class SpringContextHolder implements ApplicationContextAware,
        DisposableBean {

    private static ApplicationContext applicationContext;

    /**
     * 实现ApplicationContextAware接口, 注入Context到静态变量中.
     */
    @Override
    public void setApplicationContext(ApplicationContext applicationContext) {
        initApplicationContext(applicationContext);
    }


    private static void initApplicationContext(ApplicationContext applicationContext) {
        if (Objects.isNull(SpringContextHolder.applicationContext)) {
            SpringContextHolder.applicationContext = applicationContext;
        }
    }


    /**
     * 实现DisposableBean接口,在Context关闭时清理静态变量.
     */
    @Override
    public void destroy() throws Exception {
        SpringContextHolder.clear();
    }

    /**
     * 取得存储在静态变量中的ApplicationContext.
     */
    public static ApplicationContext getApplicationContext() {
        assertContextInjected();
        return applicationContext;
    }

    /**
     * 从静态变量applicationContext中取得Bean, 自动转型为所赋值对象的类型.
     */
    @SuppressWarnings("unchecked")
    public static <T> T getBean(String name) {
        assertContextInjected();
        return (T) applicationContext.getBean(name);
    }

    /**
     * 从静态变量applicationContext中取得Bean, 自动转型为所赋值对象的类型.
     */
    public static <T> T getBean(Class<T> requiredType) {
        assertContextInjected();
        return applicationContext.getBean(requiredType);
    }

    /**
     * 清除SpringContextHolder中的ApplicationContext为Null.
     */
    private static void clear() {
        applicationContext = null;
    }

    /**
     * 检查ApplicationContext不为空.
     */
    private static void assertContextInjected() {
        if (Objects.isNull(applicationContext)) {
            throw new IllegalStateException(
                    "applicationContext未注入,请将SpringContextHolder注入至容器内.");
        }
    }

    public static void main(String[] args) throws IOException {
        File file = new File("/data/appLogs/test2.txt");
        file.createNewFile();
    }


}
